fuel sending unit help.. (OHM range)

[rattlsnak]

I just got off the phone with the Centriod folks about getting a fuel sending unit for my fuel cell, and they need to know the OHM range of the factory unit. Could be either 90-0, or 76-6, or 240-33 ohms, or a few others. The high number usually dictates a low fuel condition. They need to know if when you disconnect the unit does the gauge go to empty? And if someone knows or could measure the ohm output of theirs with it really close to empty, or full and let me know that would be great.
Thanks!

[rattlsnak]

bump.....

[rattlsnak]

Well, for those who want to know, its @ 72.5 empty, and @ 3.5 OHMS full.

[CurtEgerer]

So is the 72.5 Ohm range consistent for all year fuel gauges? I'm having a problem in my 74 Carrera. 27 gallon Fuel Safe cell with Centroid sending unit. The dash gauge reads full when I fill the cell. But when the gauge gets down to about half, it suddenly drops to zero even though the cell is still half full. The sending unit is not marked with an Ohm rating. Thanks in advance for any help.

[moneymanager]

There are variations in gauges but the unit is pretty linear so far as I know. Email Joel in support at Centroid. I found him very helpful in sorting out an issue I had...mine only indicated 7/8 full when filled. I'm living with it for the moment but it will go back to him for recalibration this summer.

[CurtEgerer]

Cool. Thanks.

[rattlsnak]

post your results here to help others one day!

[kojo911]

here is the link to Centroid's calibration pdf. Pretty straight forward. The problems I'm having so far, the sender does not appear to be linear. That is from a full tank to a half tank the gauge is really slow (reads too full) then from half to empty it plummets rapidly. Still fiddling with it. The adjustment screws are uber sensitive so be patient while you set it up. I saw a post on a ford forum where the guy put a dab of loctite on the screws, I may try that.

http://www.fuelsafe.com/pdf/Centroid-Non%20Programmable.pdf

[moneymanager]

I returned mine to Joel and they recalibrated. Had no luck with home fixes.

[kojo911]

was/is the issue resolved? I'm in the same boat does not read full, roughly 7/8ths to 15/16s and appears to be non-linear. The gauge is roughly ten years old though, I just started sorting the car and got to it.

[moneymanager]

Mine was new; that may have made a difference. Results were good. Full is now full. THese things aren't ever perfect but mine is pretty linear. One quarter tank in my cell should be 4+ gallons, in reality I have 5 or 6 so it's conservative.

[seafeye]

Kinda old thread. Does anybody know the resistance for a fuel sending unit for a 100L fuel tank?

[seafeye]

Anything?

[911pcars]

If the sending unit is made for the fuel gauge, the empty and full resistant specs should be the same as stated.

Sherwood

[seafeye]

Ok thanks. I have a lovely 100l tank and would like to use my stock sender if possible. Maybe the 100L ones are slightly longer?

[T77911S]

if you plan to use the original unit then I would measure from the mounting surface of the sender to the bottom of the tank for both tanks. if the 100l is taller then the gauge will show empty long before it really is.

[Flojo]

sweet tank... they got real expensive by now.

[911pcars]

Originally Posted by T77911S

if you plan to use the original unit then I would measure from the mounting surface of the sender to the bottom of the tank for both tanks. if the 100l is taller then the gauge will show empty long before it really is.

Yes, you'll need a longer sending unit to measure the fuel level as it reaches the bottom of the larger capacity tank. Maybe someone can provide a contact number. I understand around $300 or so.

Sherwood

[seafeye]

Thanks. I'll look into a longer one. Or I wonder if I can modify mine.....